There has long been a need, particularly with the advent of the energy crisis, for a simple device that efficiently mixes air and any type of solid pulverized fuel in predetermined amounts. Prior devices include complicated mechanisms such as multiple baffles, carburetor-type structures, multiple valves, etc., which are highly complicated and most expensive. Additionally, such prior devices are limited to mixing only certain types of pulverized fuel. There is a dire requirement for a simple device that mixes air with any type of solid pulverized fuel such as pulverized coal, sawdust, pulverized corn husks, dried sewage, etc.